U.S. Pat. No. 3,575,146 issued to Creighton et al teaches a three switch (sensor), one cam system for determining the ignition or injection times in internal combustion engines. This system is duplicated for each cylinder in the engine.
U.S. Pat. No. 3,738,339 issued to Huntzinger et al teaches a two sensor, two cam system for determining the ignition time for each cylinder. One sensor determines a predetermined number of degrees before the top-dead center position of each cylinder and the other sensor responds to a multi-toothed cam to determine each degree of rotation of the engine crankshaft. There is required to be used in conjunction with this patent, a distributor as shown in reference U.S. Pat. No. 3,605,713, cited in Col. 2 of U.S. Pat. No. 3,738,339, to direct the ignition pulse to the correct spark plug.
U.S. Pat. No. 4,009,699 issued to Hetzler et al, in which Huntzinger is a co-inventor, shows the same two sensor, two cam arrangement for determining the ignition timing of each cylinder.
In each of the above, there was in addition to a rotating timing member, a unique switching path to direct the end results of the timing member to a particular spark plug or injector. The rotating timing member, with its two or more switch elements, never generates a unique signal for a particular spark plug or injector but relies upon another element to select the particular spark plug or injector.
U.S. Pat. No. 3,710,763 issued to Bassot et al, discloses a switch for each injector plus a synchronizing switch for synchronizing the time of operation of each of the high speed injectors to a corresponding predetermined angular position of the engine camshaft.
U.S. Pat. No. 3,702,601 issued to Gordon et al, discloses the use of four switches to generate eight pulses each engine cycle and one switch to indicate each half of the engine cycle. Thus, five switches are required to generate the eight actuation pulses.
In my U.S. Pat. No. 3,881,453, I have disclosed an electronic fuel injection triggering means utilizing a four magnets which by their angular position on a rotor with respect to the angular position of four magnetic switches will generate a binary code at eight predetermined rotor positions. The binary code will then be decoded to generate a signal identifying each injector of the eight injectors. This system has the advantage over the other prior art systems of generating a known signal within ninety degrees of revolution of the camshaft instead of a full revolution but at the cost of four switches and magnets.
The classical technique, as is illustrated in the prior art, for triggering an ignition system is also used in triggering or controlling a sequential fuel injection system. This technique utilizes two sensors such as magnetic reed switches to provide two separate signals to a counting circuit. In the case of a four cylinder engine, one switch provides a synchronization signal for initializing the counter which signal occurs once per engine cycle and is typically indicative of the number one cylinder. The other switch generates clocking signals to count a divide-by-four counter for generating four actuation pulses per engine cycle to initiate the proper injection pulses. The synchronizing signal assures that the counter states are synchronized with the correct cylinder during the engine cycle. Thus, with two sensors, sychronization does not happen until the synchronizing pulse is generated which may be one complete engine cycle after engine turn-on.
The present invention solves the problem of electrically identifying the cylinder to be injected within ninety degrees of an engine cycle by using two switches and a single lobe cam member attached to the engine camshaft. Mounted adjacent to said cam member are two proximity sensors which are mounted ninety degrees apart. Each sensor generates a binary valued electrical pulse which has a pulse width of 180.degree.. Each pulse is supplied to a decoding means wherein the binary valued pulses are decoded and then to pulse generators for generating a predetermined controlled-time electrical pulse for each injector. All this initially takes place within ninety degrees of rotation of the camshaft after engine turn-on.